A good textbook covering the basic technologies used in developing VR and AR applications.
Each chapter is devoted to a different subject (e.g. latency, tracking, graphics, displays, haptics, etc.) and is written by a different author/group. As a result, there is no common narrative voice or theme that pervades the book to tie together the disparate subjects into a unified whole, which is of course essentially for a VR/AR system to work effectively. Also, the book was translated from German, so the language isn't always the best, but it's a technical textbook and not a work of literature, and it's certainly understandable if a bit dry.
Overall, an extremely useful resource for someone who may be an expert in one area, but lacks experience in some of the others.